Pyrethroid application timing to control European corn borer (Lepidoptera: Crambidae) and minimize fumonisin contamination in maize kernels

Ostrinia nubilalis (Hübner) (European corn borer) is the main maize pest in Central and South Europe and it promotes Fusarium verticillioides infection on maize grains, which is able to produce fumonisins. The objective of this study was to determine the effect of the timing of pyrethroid treatments on European corn borer damage, fungal ear rot and fumonisin contamination. The field experiments were performed from 2005 to 2007 in NW Italy. Four application timings were compared to an untreated control. The insecticide treatments were applied at approximately 10 days intervals, starting from the end of flowering. The last treatment was performed approximately 15 days after the ECB flight peak. At harvest, the ears were rated for the incidence and severity of European corn borer damage and fungal ear rot symptoms, and the harvested kernels were analyzed for fumonisins B 1 +B 2 . In all the years, the treatments applied 7–10 days before the European corn borer adult flight peak showed the best efficacy to control insect damage on ears. Fungal ear rot and fumonisin contamination were clearly affected by European corn borer control. The occurrence of this mycotoxin in plots treated at the best pyrethroid application timing was significantly reduced, on average by 76%, compared to the untreated control. Furthermore, early insecticide applications, at the end of maize flowering, showed significantly lower fumonisin contamination than treatments applied at approximately 15 days after the adult flight peak. This research indicates that the production of maize kernels with low fumonisin content may be enhanced by a correct timing of the insecticide application against second generation European corn borer